modules/videoio/src/cap_winrt

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This source file includes following definitions.
getInstance
isStarted
closeGrabber
initGrabber
_GrabFrameAsync
CopyOutput
listDevicesTask
listDevices
// Video support with XAML

// Copyright (c) Microsoft Open Technologies, Inc.
// All rights reserved.
//
// (3 - clause BSD License)
//
// Redistribution and use in source and binary forms, with or without modification, are permitted provided that
// the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the
// following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the
// following disclaimer in the documentation and/or other materials provided with the distribution.
// 3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or
// promote products derived from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED
// WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
// PARTICULAR PURPOSE ARE DISCLAIMED.IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY
// DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES(INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT(INCLUDING
// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.

#include "cap_winrt_video.hpp"

#include <ppl.h>
#include <ppltasks.h>
#include <concrt.h>
#include <agile.h>

#include <atomic>
#include <future>
#include <vector>


using namespace ::concurrency;
using namespace ::Windows::Foundation;
using namespace ::std;

using namespace Microsoft::WRL;
using namespace Windows::Media::Devices;
using namespace Windows::Media::MediaProperties;
using namespace Windows::Media::Capture;
using namespace Windows::UI::Xaml::Media::Imaging;
using namespace Windows::Devices::Enumeration;

#include "cap_winrt/CaptureFrameGrabber.hpp"

// pull in Media Foundation libs
#pragma comment(lib, "mfplat")
#pragma comment(lib, "mf")
#pragma comment(lib, "mfuuid")

#if (WINAPI_FAMILY!=WINAPI_FAMILY_PHONE_APP) && !defined(_M_ARM)
#pragma comment(lib, "Shlwapi")
#endif

#include "cap_winrt_bridge.hpp"

Video::Video() {}

Video &Video::getInstance() {
    static Video v;
    return v;
}

bool Video::isStarted() {
    return bGrabberInited.load();
}

void Video::closeGrabber() {
    // assigning nullptr causes deref of grabber and thus closes the device
    m_frameGrabber = nullptr;
    bGrabberInited = false;
    bGrabberInitInProgress = false;
}

// non-blocking
bool Video::initGrabber(int device, int w, int h) {
    // already started?
    if (bGrabberInited || bGrabberInitInProgress) return false;

    width = w;
    height = h;

    bGrabberInited = false;
    bGrabberInitInProgress = true;

    m_deviceID = device;

    create_task(DeviceInformation::FindAllAsync(DeviceClass::VideoCapture))
        .then([this](task<DeviceInformationCollection^> findTask)
    {
        m_devices = findTask.get();

        // got selected device?
        if ((unsigned)m_deviceID >= m_devices.Get()->Size)
        {
            OutputDebugStringA("Video::initGrabber - no video device found\n");
            return false;
        }

        auto devInfo = m_devices.Get()->GetAt(m_deviceID);

        auto settings = ref new MediaCaptureInitializationSettings();
        settings->StreamingCaptureMode = StreamingCaptureMode::Video; // Video-only capture
        settings->VideoDeviceId = devInfo->Id;

        auto location = devInfo->EnclosureLocation;
        bFlipImageX = true;
        if (location != nullptr && location->Panel == Windows::Devices::Enumeration::Panel::Back)
        {
            bFlipImageX = false;
        }

        m_capture = ref new MediaCapture();
        create_task(m_capture->InitializeAsync(settings)).then([this](){

            auto props = safe_cast<VideoEncodingProperties^>(m_capture->VideoDeviceController->GetMediaStreamProperties(MediaStreamType::VideoPreview));

            // for 24 bpp
            props->Subtype = MediaEncodingSubtypes::Rgb24;      bytesPerPixel = 3;

            // XAML & WBM use BGRA8, so it would look like
            // props->Subtype = MediaEncodingSubtypes::Bgra8;   bytesPerPixel = 4;

            props->Width = width;
            props->Height = height;

            return ::Media::CaptureFrameGrabber::CreateAsync(m_capture.Get(), props);

        }).then([this](::Media::CaptureFrameGrabber^ frameGrabber)
        {
            m_frameGrabber = frameGrabber;
            bGrabberInited = true;
            bGrabberInitInProgress = false;
            //ready = true;
            _GrabFrameAsync(frameGrabber);
        });

        return true;
    });

    // nb. cannot block here - this will lock the UI thread:

    return true;
}


void Video::_GrabFrameAsync(::Media::CaptureFrameGrabber^ frameGrabber) {
    // use rgb24 layout
    create_task(frameGrabber->GetFrameAsync()).then([this, frameGrabber](const ComPtr<IMF2DBuffer2>& buffer)
    {
        // do the RGB swizzle while copying the pixels from the IMF2DBuffer2
        BYTE *pbScanline;
        LONG plPitch;
        unsigned int colBytes = width * bytesPerPixel;
        CHK(buffer->Lock2D(&pbScanline, &plPitch));

        // flip
        if (bFlipImageX)
        {
            std::lock_guard<std::mutex> lock(VideoioBridge::getInstance().inputBufferMutex);

            // ptr to input Mat data array
            auto buf = VideoioBridge::getInstance().backInputPtr;

            for (unsigned int row = 0; row < height; row++)
            {
                unsigned int i = 0;
                unsigned int j = colBytes - 1;

                while (i < colBytes)
                {
                    // reverse the scan line
                    // as a side effect this also swizzles R and B channels
                    buf[j--] = pbScanline[i++];
                    buf[j--] = pbScanline[i++];
                    buf[j--] = pbScanline[i++];
                }
                pbScanline += plPitch;
                buf += colBytes;
            }
            VideoioBridge::getInstance().bIsFrameNew = true;
        } else
        {
            std::lock_guard<std::mutex> lock(VideoioBridge::getInstance().inputBufferMutex);

            // ptr to input Mat data array
            auto buf = VideoioBridge::getInstance().backInputPtr;

            for (unsigned int row = 0; row < height; row++)
            {
                // used for Bgr8:
                //for (unsigned int i = 0; i < colBytes; i++ )
                //    buf[i] = pbScanline[i];

                // used for RGB24:
                for (unsigned int i = 0; i < colBytes; i += bytesPerPixel)
                {
                    // swizzle the R and B values (BGR to RGB)
                    buf[i] = pbScanline[i + 2];
                    buf[i + 1] = pbScanline[i + 1];
                    buf[i + 2] = pbScanline[i];

                    // no swizzle
                    //buf[i] = pbScanline[i];
                    //buf[i + 1] = pbScanline[i + 1];
                    //buf[i + 2] = pbScanline[i + 2];
                }

                pbScanline += plPitch;
                buf += colBytes;
            }
            VideoioBridge::getInstance().bIsFrameNew = true;
        }
        CHK(buffer->Unlock2D());

        VideoioBridge::getInstance().frameCounter++;

        if (bGrabberInited)
        {
            _GrabFrameAsync(frameGrabber);
        }
    }, task_continuation_context::use_current());
}


// copy from input Mat to output WBM
// must be on UI thread
void Video::CopyOutput() {
    {
        std::lock_guard<std::mutex> lock(VideoioBridge::getInstance().outputBufferMutex);

        auto inAr = VideoioBridge::getInstance().frontInputPtr;
        auto outAr = GetData(VideoioBridge::getInstance().frontOutputBuffer->PixelBuffer);

        const unsigned int bytesPerPixel = 3;
        auto pbScanline = inAr;
        auto plPitch = width * bytesPerPixel;

        auto buf = outAr;
        unsigned int colBytes = width * 4;

        // copy RGB24 to bgra8
        for (unsigned int row = 0; row < height; row++)
        {
            // used for Bgr8:
            // nb. no alpha
            // for (unsigned int i = 0; i < colBytes; i++ ) buf[i] = pbScanline[i];

            // used for RGB24:
            // nb. alpha is set to full opaque
            for (unsigned int i = 0, j = 0; i < plPitch; i += bytesPerPixel, j += 4)
            {
                // swizzle the R and B values (RGB24 to Bgr8)
                buf[j] = pbScanline[i + 2];
                buf[j + 1] = pbScanline[i + 1];
                buf[j + 2] = pbScanline[i];
                buf[j + 3] = 0xff;

                // if no swizzle is desired:
                //buf[i] = pbScanline[i];
                //buf[i + 1] = pbScanline[i + 1];
                //buf[i + 2] = pbScanline[i + 2];
                //buf[i + 3] = 0xff;
            }

            pbScanline += plPitch;
            buf += colBytes;
        }
        VideoioBridge::getInstance().frontOutputBuffer->PixelBuffer->Length = width * height * 4;
    }
}


bool Video::listDevicesTask() {
    std::atomic<bool> ready(false);

    auto settings = ref new MediaCaptureInitializationSettings();

    create_task(DeviceInformation::FindAllAsync(DeviceClass::VideoCapture))
        .then([this, &ready](task<DeviceInformationCollection^> findTask)
    {
        m_devices = findTask.get();

        // TODO: collect device data
        // for (size_t i = 0; i < m_devices->Size; i++)
        // {
        //   .. deviceInfo;
        //   auto d = m_devices->GetAt(i);
        //   deviceInfo.bAvailable = true;
        //   deviceInfo.deviceName = PlatformStringToString(d->Name);
        //   deviceInfo.hardwareName = deviceInfo.deviceName;
        // }

        ready = true;
    });

    // wait for async task to complete
    int count = 0;
    while (!ready)
    {
        count++;
    }

    return true;
}


bool Video::listDevices() {
    // synchronous version of listing video devices on WinRT
    std::future<bool> result = std::async(std::launch::async, &Video::listDevicesTask, this);
    return result.get();
}
/* [<][>][^][v][top][bottom][index][help] */
root/modules/videoio/src/cap_winrt_video.cpp

DEFINITIONS
